title: Effect of molecular weight profile of sorghum proanthocyanidins on resistant starch formation.
abstract: BACKGROUND
  There is a growing interest to increase resistant starch (RS) in foods through natural modification of starch. Sorghum tannins (proanthocyanidins, PAs) were recently reported to interact with starch, increasing RS. However, there is no information about how the molecular weight profile of PAs affects RS formation. This study investigated how different-molecular-weight PAs from sorghum affected RS formation in different starch models.
  
  
  RESULTS
  The levels of RS were higher (331-437 mg g(-1)) when high-amylose starch was cooked with phenolic extracts containing mostly high-molecular-weight PAs compared with extracts containing lower-molecular-weight PAs or monomeric catechin (249-285 mg g(-1)). In general, binding capacity of PAs with amylose increased proportionally with molecular weight. For example, the percentage of PAs bound to amylose increased from 45% (PAs with degree of polymerization (DP) = 6) to 94% (polymeric PAs, DP > 10). The results demonstrate that molecular weight of the PAs directly affects their interaction with starch: the higher the molecular weight, the stronger the binding to amylose and the higher the RS formation.
  
  
  CONCLUSIONS
  Polymeric PAs from sorghum can naturally modify starch by interacting strongly with amylose and are thus most suitable to produce foods with higher RS.
authors.affiliation: Cereal Quality Lab, Department of Soil & Crop Sciences, Texas A&M University, 370 Olsen Blvd, TAMU 2474, College Station, TX 77843-2474, USA.
authors.forename: Frederico
authors.initials: F
authors.lastname: Barros
authors.forename: Joseph
authors.initials: J
authors.lastname: Awika
authors.forename: Lloyd W
authors.initials: LW
authors.lastname: Rooney
mesh_terms: D000688:Amylose / Q000737:chemistry; D003296:Cooking; D004032:Diet; D002523:Edible Grain / Q000737:chemistry; D006801:Humans; D008970:Molecular Weight; D058105:Polymerization; D044945:Proanthocyanidins / Q000737:chemistry*; D012639:Seeds; D045868:Sorghum / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*
chemical_list: D044945:Proanthocyanidins; D013213:Starch; D000688:Amylose
keywords: amylose; molecular weight; proanthocyanidins; resistant starch; sorghum